Process of treating materials.



tmrrn snare PATENT onnron.

FREDERICK W. YOST, OF CHICAGO. ILLINOIS. ASSIGNOR TO EDWARD A. BERN, OFCHICAGO, ILLINOIS.

PROCESS OF TREATING MATERIALS.

Specification of Letters Patent.

Patented July 3, 1191i 7.

Renewed October 10. 1912. Serial No.

To 0?] 10720112 it may concern.

Be it known that I. Fnnmznrcn W. YosT, a citizen of the I'nited States,residing at Chicago. in the county of (00k and State of Illinois. haveinvented certain new and useful Improvements in Processes of TreatingMaterials. of which the following is a SPQCI? fication.

My invention relates to thetreat-ment of material: and it comprises aprocess wherein a mass of material is calcinedfroasted or clinkered bymeans of a current of reactionsupporting gas conducted through the massand by means of heat applied to the gas en- 'trance surface-of the massduring the period of reaction: and it comprises more particularly. butnot exclusively. a process wherein a body of furnace gases is used toheat the upper surface of a stationary or movable mass of finely dividedmaterial and all or a partof the furnace gases are conducted through themass to propagate a calcinin roasting. or clinkering reaction throughthe mass: all as more fully hereinafter set forth and as claimed.

Many ores and minerals liminary change in their physical condition orchemical state to better adapt them for use in metallurgical ormanufacturing arts. Finely divided iron ores. blast furnace flue dust.iron ore concentrates and other similar materials arezulvantageouslyclinkered to fit them for use in the blast furnace, and when thesematerials have aQhigh sulfur content they also require roastin Forspecial metallurgical purposes it may be desirable to reduce thesematerials to lower oxids of iron or to sponge iron. Sulfid ores areroasted to partially or wholly convert them into oxids to meet therequirements of various smelting and refining operations. Sulfid orefines or concentrates require clinkering to adapt them for smelting instack furnaces and to avoid the more. expensive method of smelting inreverberatory furnaces. Materials like chrome ore, magnesite, bauxiteand clay. are calcined to eliminate chemically combined water or carbondioxid. Finely groimd mixtures of clay and limestone or suitableequivalents of these materials. are calcined and clinkered to makecement clinker. In certain prior applicarequire $01119 PIG- tions nowmatured into Patents 1,003,682, 1.003.683 and 1,003,6Si. all ofSeptember 19, 1911, I describe and claim processes which compriseforming such material into a mass adapted for the propagation of one ormore of the described reactions, initiating a reaction at a surface ofthe mass. conducting a reaction-producing or reaction-supporting gasthrough the mass toward the surface of initial reaction, and by suitablecontrol of conditions propagating one or more of the described reactionsthrough the mass in one or more directions. In another and c0- pendingapplication, erial Number 551L712, filed April 11. 1910. I describe andclaim a process which comprises forming similar materials into-a massadapted for the propagation of one or more of the described reactions.initiating a reaction in the mass, conducting two currents ofreaction-producing or reaction-supporting gas through the mass indifi'erent directions, and by suitable control of conditions propagatingone or more of the described reactions through the mass. In these priorprocesses the calcining. roasting or clinkering reaction is usuallypropagated through a portion of the mass in a direction opposite to thatof the gas current. and this portion of the mass must have a relativelylarge content of fuel. In the present invention the reaction ispropagated through the entire mass in the same direction as that of thereactionsupporting or reaction-producing gas. and the fuel content ofthe mass can therefore be reduced to the lowest attainable limit. Theadaptability of the present process to the treatment of materialcontaining the minimum quantity of naturally or artificially mixed fuel.is one of the important objects of the invention. In the older anddiscontinuous forms of pot roasting processes, a layer of ignited fuelor of hot calcines is interposed between the material to be clinkeredand the grate in the lower part of the pot roasting apparatus. The heattransmitted from this layer of fuel or of hot calcines. to the lowerportion of the charge is used to initiate the clinker-ing reaction: butthe clinkering zone is propagated through the body of the charge solelyby the internal combustion of the contained fuel. In the continuous formof the pot roasting process the moving hearth carries the charge under asuitable. burner or igniting device. where the upper surface of thecharge is ignited; and the moving hearth then carries the ignitedportion of the charge away from the burner and over a suitable suctionbox. where a downward draft of air is conducted through the charge. Theigniting flame acts on the upper surface of a given portion of thecharge for a very short period of time. and the clinkering zone ispropagated through the body of the charge wholly by the heat developedby the internal combustion of the fuel in the charge while the steadilyentering cold air serves to reduce the temperature at the surface of thecharge. The various forms of the pot roasting process have been appliedprincipally to the clinkering of metallic sulfids relatively high insulfm: Such material is adapted for treatmentby pot roasting because arelatively small amount of heat suflices to ignite the charge. and whenignited a clinkering .reaction can be readily propagated through thecharge by a current of cold air. introduced at the ignited surface andconducted through the interior of the charge. It is evident that none ofthe various forms of the pot roasting process is well adapted for theclinkering of metallic sulfids very low in sulfur. or to the clinkeringof artificial mixtures of metallic oxids with carbonaceous fuel. such asfinely divided coal or coke which have a relatively high ignitingtemperature. In the present proces such materials may be readily andeconomically treated. because the charge may be maintained under theinfluence of the heating gases during the entire period of operation.and the clu'rent of gases used to propagate the reaction may beconducted through the charge at any required temperature and may haveany desired composition. The ability to treat material containing smallpercentages of fuel and having a high temperature of reaction. isanother one of the important objects of the present invention.

My present proces can be carried on discontinuously in any reverberatoryroasting furnace provided with a perforated hearth, or it can be carriedon continuously in well known forms of chain grate stoker furnaces. Theparticular form of apparatus used for carrying on this process. is notmaterial to the present invention in its broader aspects.

My proce may be applied to a mass of any pulverous or granular materialwhich is capable of undergoing an internal propagative reaction. whetherthis capability is natural to the material. as in sulfid ores: orwhether it is'imparted by the artificial admixture ofreaction-supporting materials with the other materials of the mass. asby the mixing of powdered fuel with finely diof fine Mesaba ore or blastfurnace flue dust.

may be mixed with powdered fuel such as bituminous coal screenings. cokebreeze or anthracite coal dust, to form a mass adapted for treatment'bymy process; materials intended for making Portland cement. such aspulverized mixtures of clay and limestone either naturally orartificially mixed. or

partly naturally and partly artificially mixed. may he treated by myproces by first adding to the material a finely divided fuel: ormaterials like chrome ore. magnesite. bauxite or clay. which by ordinarymethods are not readily calcined. may be mixed with suitable fuel andtreated by my process in which the fine state of division and theintimate contact of the material with the fuel materially hastens thecalcining operation. Many other materials which are capable ofundergoing a propagative reaction when formed into a suitable mam. maybe treated by my procesa and I regard its application to all suchmaterials as within the scope of my invention.

As an advantageous embodiment of the invention. my procemmay be appliedto the clinkering of finely divided iron oxid. This material may be apulverous natural ore. the granular product of a concentration processor a finely divided metallurgical waste such as blast furnace flue dustor fine pyrites cinder. The fine iron oxid is mixed with powdered coal.coke. charcoal or other combustible material. and is charged into anysuitable furnace of one of the types referred to. Any fuel adapted foruse in a reverberatory furnace. may he used to generate flame or furnacegases. which are conducted through the furnace in contact with the uppersurface of the charge. A. portion or preferably all of the furnace gasesare conducted downward through the charge. and through the perforatedhearth or grate into a suitable outlet flue. The charge is heateduniformly and progressively from the top to the bottom. and a clinkeringreaction initiated at the upper surface is propagated downward throughthe charge. but ata slower rate than the progress of the heating zone.The furnace gases must be maintained at a high enough temperature toinitiate the clinkering reaction at the upper surface of the charge.'andthe gases must also be sutficiently oxidizing to propagate the reactionthrough the charge. 'hen the process is carried on discontinuously in areverberameanest tory furnace with a fixed perforated hearth, it isdesirable to discontinue the downward current of gases while a layer ofunclinkered and cold material remains adjacent to the perforated hearth,to cool the outgoing waste gases to a safe temperature before theirpassage through the perforated hearth. If preferred a-layer of crushedlimestone, clinker or other suitable material may be interposed betweenthe perforated hearth and the lower surface of the charge to absorb theexcess of heat in the escaping gases, and the clinkering reaction maythen be propagated to the lower surface of the charge. The process mayalso be carried on discontinuously in a chain grate stoker type offurnace or any other type of movable hearth furnace by holding thecharge at rest in the furnace during the time of treatment and thenmoving the charge so as to carry the clinkered material out of thefurnace chamber and a new charge of material into the furnace fortreatment. When the process is carried on continuously in a chain gratestoker type of furnace, the charge moves continuously from the entranceend of the furnace to the exit end, the furnace gases are continuouslygenerated by the combustion of extraneous fuel, and all or a portion ofthese gases are continuously conducted downward through the charge andinto a suitable outlet flue. By suitably regulating the speed of themoving hearth, the charge maybe brought to the exit end of the furnacewith a heat insulating layer of unclinkered and cold material adjacentto the hearth, and this unclinkered portion of the charge may bescreened out of the finished clinker and may be returned to the furnacefor retreatment. When a layer of crushed limestone or crushed clinker isfed upon the moving hearth to serve as the heat insulating layer, a partof this layer fuses to the clinkering portion of the charge; and theremaining part of this layer may be separated from the finished clinkerby screening and may be re-used in the furnace. carbonaceous material inthe charge need only be sufiicient to cause the clinkering reaction tobe initiated, since the charge is heated up to the reacting temperatureby the furnace gases. When it is desired to produce clinker containingthe lower oxids of iron, or

. wholly reduced ing conditions Within the metal such as sponge iron, itto maintain more highly reduccharge than those is necessary Such highlyreducing conditions may be secured by the use of larger propor- 60 tionsof carbonaceous material in the charge and'by the use of reducingfurnace gases.

My process may also be used for roasting and clinkering finely dividedsulfid ores, concentrates or flue dust. The finely divided sulfurbearing material is charged into one The i of the types of furnacereferred to, and furnace gases generated by the combustion furnace incontact with the upper surface of the charge. of the furnace gases areconducted downward through the charge. and through the perforated hearthor grate into a suitable outlet flue. A clinkering reaction is initiatedat the upper surface of the charge and is propagated downward to thelower surface by suitably controlling the composition, temperature andpressure of 'the furnace gases. When it is desired to use the wastesulfur gases for sulfuric acid manufacture or other by-product purpose,the furnace gases may be wholly composed of atmos pheric air highlyheated so that they will initiate the clinkering reaction. 'hen thematerial to be heated is too low in sulfur for the propagation of theclinkering reaction, other elements may be added to the charge.

When this process is applied to the clinkering of cement materials, thefinely ground raw mix is intimately mixed with powdered carbonaceousmaterial, such as coal, coke, or charcoal and is charged into a suitablefurnace of one ofthe types described. The

of a suitable fuel. are conducted through the A portion or preferablyall furnace gases generated by the combustion of a suitable fuel,are'conducted through the furnace in contact with the upper surface ofthe charge to initiate a clinkering reaction at that surface, and thefurnace gases conducted downward through the charge are used topropagate the clinkering reaction to the lower surface. The process maybe carried on discontinuously in a fixed hearth furnace or continuouslyin a furnace of the chain grate Stoker type, and the method of operationmaybe similar in a general way to that used for making iron oreclinker.-

In the treatment of the materials described in these examples, variousmodifications will suggest themselves to those skilled in the art. Itmay be desirable to moisten the charge to form interstices for theuniform distribution of the gas current through the niass. The furnacegases used to heat the upper surface of the charge and conducted throughthe charge, may be oxidizing, neutral or reducing. The temperature inthe zone of reaction may be regulated or the character of reaction maybevaried by the addition of steam or other modifying elements, to the gascurrent conducted through the mass. Vhere the ash from the combustion ofsolid fuel is an undesirable ingredient of the finished product, liquidor semi-liquid fuel may be used as the heat developing component. Withmaterial of a highly refractory nature, it may be desirable to add aflux to lower the clinkering temperature. When the process is carried oncontinuously in a chain grate stoker type of furnace, the furnace gasesmay be conducted through the furnace chamber in the same direction asthat of the moving charge or in the opposite direction.

I do not wish to be limited to the treatment of the materials describedin the examples, nor do I wish to be limited to the kinds of treatmentthere described. It will be evident to those skilled in the art thatthis invention applies to the treatment of any material, or any mixtureof materials, of such a nature that one or more reactions can bepropagated through the mass in the same direction as that of a currentof gas which is conducted through the mass under the influence of heatapplied in the manner described. Itwill be further evident that thekinds of treatment accorded the material are not limited to calcining,roasting, or clinkering, but may include any treatment, which can becarried on by the methods described.

It will also be evident that the gas current can be either an oxidizingor a reducing agent, provided that under suitable control .of conditionsit has the property of propagating the reaction in the manner described.

It is to be understood that the words finely divided, as herein used,have reference to any degree of subdivision that best adaptsthe'material to treatment by my process, as some materials respond totreatment better when=in a relatively coarse condition while othermaterials respond to treatment only when in afinely divided state. It isto be also understood that where the materials are described in theclaims as containing various components, the various components maybeoriginally contained in the material or they may be added to thematerial to prepare it for treatment.

Vhat I claim is:

1. The process of treating finely divided material capable of beingclinkered, which comprises heating a surface of a mass of the materialdining the whole time of treatment, introducing a current of gas at thesame surface of the mass, conducting the current of gas through themass, and controlling conditions so as'to propagate a clinkeringreaction through the mass.

2. The process of treating finely divided material containingcombustible components, which comprises heating a. surface of a mass ofthe material during the whole time of treatment, introducing a currentof gas at I the same surface of the mass, conducting the current of gasthrough the mass, and controlling conditions so as to propagate aclinkering reaction throughthe mass.

3. The process of treating finely divided material capable of beingclinkeled, which comprises maintaining a body of hot gases in contactwith a surface of a mass of the material, conducting hot gases throughthe mass from the same surface, and controlling conditions so as topropagate a clinkering reaction through the mam.

l. The process of treat-ing finely divided material containingcombustible components, which comprises maintaining a body of furnacegases in contact with a surface of a mass of the material. conductingfurnace gases through the mass from the same sur face. and propagating aclinkering react-ion through the mass.

5. The process of treating finely divided material containing combutlblE components,

which comprises transmitting heat from a moving body 'of furnace gasesto substantially the entire surface of a mass of the material undergoingtreatment, conduct-ing furnace gases through the mass from the samesurface. and propagating a clinkering reaction through the mass.

6. The process of treating finely divided material capable of beingclinkered, which comprises forming a mass of the material on aperforated furnace-hearth, heating a surface of the mass with areverberatory furnace flame, introducing a current of gas at the samesurface of the mass, conducting a current of gas through the mass, andcontrolling conditions so as to propagate a clinkering reaction throughthe mass.

7. The process of treating finely divided material containingcombustible components, which comprises forming a mass of the materialon a perforated furnace-hearth, transmitting heat from a body ofreverberatory furnace gases to a surface of the mass, con

ducting hot gases through the mass from the same surface, andpropagating a clinkering reaction through the mass.

8. The process of treating finely divided material containingcarbonaceous components, which comprises forming a mas of the materialon a. perforated furnace-hearth, transmitting heat from a body ofreverberatory furnace gases to a surface of the mass, conducting hotgases through the mass from the same surface. and propagating aclinkering reaction through the mass.

9. The process of treating finely divided material containingcombustible components, which comprises forming a mass of the materialon a perforated furnace-hearth, main taining a body of reverberatoryfurnace gases in contact with a surface of the mass, conducting hotgases through the mass from the same surface, and propagating aclinkering reaction through the mass.

10. The process of treating finely divided material capable of beingclinkered, which comprises forming a mass of the material on aperforatedfurnace-hearth, heating the upper surface of the mass with areverberatory furnace flame, conducting a current of gas downwardthrough the mass, and controlling conditions so as to propagate aclinkering reaction through the mass.

ll. The process of treating finely divided material containingcombustible components. which comprises forming a mass of the materialon a. perforated furnace-hearth. transmitting heatfrom a body ofreverberatory furnace gases to the upper surface of the mass. conductinghot gases downward through the mass. and propagating a clinkeringreaction through the mass.

12. The process of treating finely divided material containingcarbonaceous components. which comprises forming a mass of the materialon a perforated furnace-hearth, maintaining a body of reverberatoryfurnace gases in contact with the upper surface of the mass. conductinghot gases downward through the mass, and propagating a clinkeringreaction throughthe mass.

13. The process of treating finely divided material containingcombustible components, which comprises forming a layer of heatinsulating material on a perforated furnaceheart-h, charging a mass ofthe finely divided material on the layer of heat insulating material.transmitting heat from a body of reverberatory furnace gases to theupper surface of the mass, conducting hot gases downward through themass, and propagating a clinkering reaction through the mass.

It. The process of treating finely divided material containingcarbonaceous components, which comprises forming a layer of heatinsulating material on a perforated furnace-hearth,charging a mass ofthe finely divided material on the layer of heat insulating material,maintaining a body of reverberatory furnace gases in contact with theupper surface of the mass, conducting hot gases downward through themass, and propagating a clinkering reaction through the mass.

15. The process of treating finely divided material containingcombustible components, which comprises forming a movable mass of thematerial on a perforated furnace-hearth, transmitting heat from a bodyof reverberatory furnace gases to a surface of the movable mass,conducting hot gases through the movable mass from the same surface, andpropagating a clinkering reaction through the movable mass.

16. The process of treating finely divided material capable of beingclinkered which comprises forming a movable mass of the material on aperforated furnace-hearth, transmitting heat from a body ofreverberatory furnace gases to the upper surface of the movable mass,conducting hot gases downward through the movable mass, and controllingconditions so as to propagate a clinkering reaction through the movablemass. Y

17. The process of treating finely divided material containingcombustible components, which comprises forming a movable mass of thematerial on a perforated furnacehearth. transmitting heat from a body ofreverberatory furnace gases to the upper surface of the movable mass,conducting hot gases downward through the movable mass, and propagatinga clinkering reaction through the movable mass.

18. The process of treating finely divided material containingcarbonaceous components. which comprises forming a movable mass of thematerial on a perforated furnace-hearth, maintaining a body of reverberatory furnace gases in contact with the upper surface of the movablemass, conducting hot gases downward through the movable mass, andpropagating a clinkering reaction through the movable mass.

19. The process of treating a finely divided oxid-ore mixture containingcombustible components. which comprises forming a movable mass of themixture on a perforated furnace hea rth. transmitting heatfrom a body ofreverberatory furnace gases to the upper surface of the movable mass.conducting hot gases downward through the movable mass, and propagatinga clinkering reaction through the movable mass.

20. The process of treating a finely divided oxid-ore mixture containingcombustible components, which comprises forming a movable mass of themixture on a perforated furnace-hearth. interposing a layer of heatinsulating material between the perforated hearth and the oxid-oremixture, maintaining a body of reverberatory fur nace gases in contactwith the upper surface of the movable mass. conducting-hot gasesdownward through the movable mass, and propagating a clinkering reactionthrough the movable mass.

2L The process of continuously treating finely divided material capableof being clinkered, which comprises continuously feeding the material toa moving perforated furnace-hearth to form a moving mass of thematerial. continuously heating the upper surface of the moving mass witha reverberatory furnace flame. continuously conducting a current of gasdownward through the moving mass, and controlling conditions so as tocontinuously propagate a clinkering reaction through the moving mass.

22. The process of continuously treating finely divided materialcontaining combustible components, which comprises continuously feedingthe material to a moving perforated furnace-hearth to form a moving massof the material, continuously transmitting heat from a body ofreverberatory furnace gases to the upper surface of the moving mass,continuously conducting hot gases downward through the moving mass, andcontinuously propagating a clinkering reaction through the moving mass.

23. The process of continuously treating finely divided materialcontaining carbonaceous components, which comprises continuously feedingthe material to a moving perforated furnace-hearth to form a moving massof the material. continuously transmitting heat from a body ofreverberatory furnace gases to the upper surface of the moving mascontinuously conducting hot gases downward through the moving mas, andcontinuously propagating a clinkering reaction through the moving mass.7

2- The process of continuously treating a finely divided oxid-oremixture containing combustible components, which comprises continuouslyfeeding the mixture to a moving perforated furnace-hearth to form amoving mass of the mixture, continuously transmitting heat from a bodyof reverberatory furnace gases to the upper sin-face of the moving mass,continuously conduct-ing hot gases downward through the moving mass, andcontinuously propagating a clinkering reaction through the moving mass.

25. The process of continuously treating a finely divided oxid-oremixture containing combustible components, which comprises continuouslyfeeding a layer of heat insulating material to a moving perforatedfurnace-hearth, continuously feeding the oxidore mixture on top of theheat insulating layer to form a moving mass, continuously transmittingheat from a body ofreverberatory furnace gases to the upper surface ofthe moving mass, continuously conducting hot gases downward through themoving mass, and continuously propagating a clink ering reactiontln'ough the oxid-ore mixture.

26. The proce of continuously treating finelyv divided iron oxid, whichcomprises mixing with the iron oxid the minimum quantity of finelydivided fuel required to form a mixture capable of being clinkered;continuously feeding a layer of heat insulating material to a movingperforated furnace-hearth; continuously feeding the iron oxid mixtru'eon top of the heatinsulating layer to form a moving mass; continuouslytransmitting heat from a body of reverberatory furnace gases to theupper surface of the moving mass: and continuously conducting hotgasesdownward through the moving mass; the conditions relating to thecomposition of the iron oxid mixture, the composition, temperature andpressure of the hot gases, and the speed of the moving hearth, being socorrelated as to continuously initiate a clinkering reaction at theupper surface of the moving mass, and so as to continuously propagatethe clinkering reaction downward through the moving mass.

In testimony whereof I have hereunto set my hand this 28th day of April,1910, in the presence of two witnesses.

FREDERICK w. YOST.

Witnesses War. P. McMUxx, EDWARD A. BERN.

